linux-kernel - [PATCH 1/1] vfio-ccw: fence off transport mode

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Message-Id: <20180222153959.31272-2-cohuck@redhat.com>
Date:   Thu, 22 Feb 2018 16:39:59 +0100
From:   Cornelia Huck <cohuck@...hat.com>
To:     Dong Jia Shi <bjsdjshi@...ux.vnet.ibm.com>,
        Halil Pasic <pasic@...ux.vnet.ibm.com>
Cc:     linux-s390@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Cornelia Huck <cohuck@...hat.com>
Subject: [PATCH 1/1] vfio-ccw: fence off transport mode

vfio-ccw only supports command mode for channel programs, not transport
mode. User space is supposed to already take care of that and pass us
command-mode ORBs only, but better make sure and return an error to
the caller instead of trying to process tcws as ccws.

Signed-off-by: Cornelia Huck <cohuck@...hat.com>
---
 drivers/s390/cio/vfio_ccw_fsm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index c30420c517b1..ff6963ad6e39 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -124,6 +124,11 @@ static void fsm_io_request(struct vfio_ccw_private *private,
 	if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) {
 		orb = (union orb *)io_region->orb_area;
 
+		/* Don't try to build a cp if transport mode is specified. */
+		if (orb->tm.b) {
+			io_region->ret_code = -EOPNOTSUPP;
+			goto err_out;
+		}
 		io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),
 					      orb);
 		if (io_region->ret_code)
-- 
2.13.6